Biology subjects
Publications and source records attributed to Karampelias, M..
Jasmonic and salicylic acids are the major hormones involved in plant response to pests and pathogens. Here, we engineered autoluminescent plants that report activity of these hormones with up to 53-fold contrast. Using consumer-grade cameras, we imaged reporter Arabidopsis thaliana and Nicotiana benthamiana plants throughout normal development, and in response to attacks of pests and pathogens.
Brassinosteroid plant hormones are involved in growth, biotic and abiotic-stress signaling, but functional analysis of its multiple receptors has largely focused on the ubiquitously expressed BRASSINOSTEROID INSENSITIVE 1 (BR1). The vascular-expressed brassinosteroid receptor kinase BRI1-LIKE 3 (BRL3) has a specific and essential role in Arabidopsis adaptation to drought and elevated temperature. However, the mechanistic understanding of BRL3 function and regulation is scant. Here, we show the dehydrin ERD14 colocalizes with BRI1 and BRL3 at the plasma membrane and physically interacts with these receptors through the ERD14Lys domain for proper receptor recruitment. erd14 mutants internalize BRL3-GFP and revert drought-resistant BRL3 over-expression phenotypes. BRL3 activation and downstream signaling events, including dephosphorylation of BES1 transcription factor, depend on the chaperone function of ERD14. Our study shows how proper chaperoning by ERD14 regulates BRL3 subcellular localization and activity of the vascular receptor, prompting re-examination of models of brassinosteroid-receptor functional diversification in plant adaptation to abiotic stress from specific cells of the vascular systems.
The use of beneficial microbes to mitigate drought stress tolerance of plants is of great potential albeit little understood. We show here that a root endophytic desert bacterium, Pseudomonas argentinensis sp. SA190, enhances drought stress tolerance in Arabidopsis. Transcriptome and genetic analysis demonstrate that SA190-induced root morphogenesis and gene expression is mediated via the plant abscisic acid (ABA) pathway. Moreover, we demonstrate that SA190 primes the promoters of target genes in an epigenetic manner which is ABA-dependent. Application of the SA190 priming technology on crops is demonstrated for alfalfa in field trials, showing enhanced performance under desert agriculture conditions. In summary, a single beneficial root bacterial strain can help to perform agriculture under drought and water limiting conditions. Synopsis O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=161 SRC="FIGDIR/small/522604v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@b0bd17org.highwire.dtl.DTLVardef@14e3262org.highwire.dtl.DTLVardef@cdd103org.highwire.dtl.DTLVardef@5526a0_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LIBeneficial root endophyte Pseudomonas argentinensis sp. SA190 confers drought tolerance in plants C_LIO_LISA190 modulates the expression of genes under drought stress in an ABA-dependent manner C_LIO_LISA190 primes genes via H3K4me3 histone mark enrichment C_LIO_LISA190 alters host plant physiology by improving the plant water status C_LIO_LISA190 enhances crop performance in open field conditions with limited irrigation C_LI
O_LIDistribution of auxin within plant tissues is of great importance for developmental plasticity, including root gravitropic growth. Auxin flow is directed by the subcellular polar distribution and dynamic relocalization of auxin transporters such as the PIN-FORMED (PIN) efflux carriers, which can be influenced by the main natural plant auxin indole-3-acetic acid (IAA). Anthranilic acid (AA) is an important early precursor of IAA and previously published studies with AA analogues suggested that AA may also regulate PIN localization.\nC_LIO_LIUsing Arabidopsis thaliana as a model species, we studied an AA-deficient mutant displaying agravitropic root growth, treated seedlings with AA and AA analogues and transformed lines to over-produce AA while inhibiting its conversion to downstream IAA precursors.\nC_LIO_LIWe showed that AA rescues root gravitropic growth in the AA-deficient mutant at concentrations that do not rescue IAA levels. Overproduction of AA affects root gravitropism without affecting IAA levels. Treatments with, or deficiency in, AA result in defects in PIN polarity and gravistimulus-induced PIN relocalization in root cells.\nC_LIO_LIOur results reveal a previously unknown role for AA in the regulation of PIN subcellular localization and dynamics involved in root gravitropism, which is independent of its better-known role in IAA biosynthesis.\nC_LI